[Br-].[C:2]([CH2:4][CH2:5][CH2:6][CH2:7][P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)#[N:3].CC(C)([O-])C.[K+].[CH2:33]([N:40]1[CH2:45][CH2:44][C:43](=O)[CH2:42][CH2:41]1)[C:34]1[CH:39]=[CH:38][CH:37]=[CH:36][CH:35]=1>O1CCCC1>[CH2:33]([N:40]1[CH2:45][CH2:44][C:43](=[CH:7][CH2:6][CH2:5][CH2:4][C:2]#[N:3])[CH2:42][CH2:41]1)[C:34]1[CH:39]=[CH:38][CH:37]=[CH:36][CH:35]=1To a suspension of 4-cyanobutyltriphenylphosphonium bromide (21.80 g) in tetrahydrofuran (100 ml) was added potassium tert-butoxide (5.76 g) in tetrahydrofuran (50 ml) over 30 minutes at 0° C. After 1 hour, a solution of 1-benzyl-4-piperidone (8.84 g) was added to the mixture over 30 minutes at 0° C. The mixture was stirred at ambient temperature for 1 hour, poured into ice-water and extracted with ethyl acetate. The extract was washed with brine, dried over magnesium sulfate and evaporated in vacuo. The residue was chromatographed on alumina eluting with chloroform/hexane (1:1) and the fractions containing the object compound were combined and evaporated to afford 1-benzyl-4-(4-cyanobutylidene)piperidine (9.8 g) as an oil.
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